I just started a new job in the quality assurance department of a software company. I filled out an employment application, went through interviews, and accepted the position thinking I would be an employee. Now, they want me to sign an agreement saying that I'm an independent contractor. I won't get benefits, and they won't withhold payroll taxes. But I'll be working at their office, 40 hours a week, under their supervision. Am I really an independent contractor?